Apparatus and method for synchronizing digital distance pulse counters

ABSTRACT

A stationary switch having a defined response time is positioned along the travel path of a moving object and provides a signal for multiplying the distance pulses corresponding to the travel position of the moving object during the response period. A lead counter is connected to a pulse generator coupled to the moving object, which produces the distance pulses, and to the switch, and stores the distance pulses and the signal provided by the switch. A distance pulse counter is coupled to the pulse generator and to the lead counter in a manner whereby the distance pulse counter is reset in accordance with the count position of the lead counter.

United States Patent 1151 3,648,029

Ungnadner Mar. 7, 1972 [54] APPARATUS AND METHOD FOR 2,903,093 9/1959Lusti et 340/19 X SYNCHRONIZING DIGITAL DISTANCE g s el 0e er ...23s 98u PULSE COUNTERS 3,564,216 2/1911 Laycak .235/92 s11 [72] Inventor:Friedrich Ungnadner, Erlangen, Germany P E M dR.W'lb [73] Assignee:Siemens Aktiengesellschaft, Berlin and g g z E:$$: 2:2}: j

Mumch Germany Att0rney-Curt M. Avery, Arthur E. Wilfond, Herbert 1.. 2Filed; Man 9 9 0 Lerner and Daniel J. Tick 211 App]. No.: 17,564 57ABSTRACT A stationary switch having a defined response time is posi-[30] Foreign Application Priority Data tioned along the travel path of amoving object and provides a signal for multiplying the distance pulsescorresponding to the Mar. 13,1969 Germany ..P l9 12 663.7 travelposition of the moving object during the response period. A lead counteris connected to a pulse generator cou- [52] US. Cl. ..235/92 DN, 235/92R, 235/92 CC, pled to the moving Object, which produces the distancepulses 235/92 340/211 235/92 and to the switch, and stores the distancepulses and the signal [51 Int. Cl. ..G06m 1/28 id d b th s itch, Adistance pulsg counter is coupled to [58] Field of Search..235/92,6l,20,70, 290,57, the pulse generator d to th l d t r in amanner 235/ 21 whereby thedistance pulse counter is reset in accordancewith the count position of the lead counter. [56] References Cited t 9Claims, 3 Drawing Figures UNITED STATES PATENTS 3,239,138 3/1966Loeffler ..235/98 PULSE GENERATOR 5 DRIVING PULLEY 1 I I I DEVICE 12OPTICAL INDICATING lflb PULLEY DRIVE L 5a DEVICE 11 0 1121 .l l

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MULTIVIBRATUR 19 APPARATUS AND METHOD FOR SYNCHRONIZING DIGITAL DISTANCEPULSE COUNTERS DESCRIPTION OF THE INVENTION The invention relates todigital distance pulse counters. More particularly, the inventionrelates to apparatus and a method for synchronizing digital distancepulse counters.

To measure the distance travelled or moved by a moving object, it isknown to emit digital distance or path pulses along the travel path. Thepulses are produced by a pulse generator which is suitably mounted on orcoupled with the moving object. The pulses are subsequently stored in apulse counter. The count position of the distance pulse counter is thusan indication of the position of the moving object. The indication ofthe position of the moving object is accurate, however, only as long asperfect emission and transmission of pulses occurs and the pulsegenerator and the moving object are closely joined to each other. Whenlonger distances or paths are to be measured, there is always apossibility that a pulse may be skipped or an interferring pulse may beincluded with the distance pulses. There is also a possibility thatthere may be slippage or play in the coupling between the pulsegenerator and the moving object. In order to preclude theredifficulties, and to insure perfect accuracy, the position of the pulsecounter should be synchronized, from time to time. That is, the pulsecounter should be examined with regard to the actual position of themoving object and corrected, if necessary.

Switching devices may be provided at specific stationary points alongthe path of the moving object. The switching devices may be operated bythe moving object during its movement past said devices. Each switchingdevice produces a signal when the moving object passes it and the signalproduced by the switching device is then utilized to set the pulsecounter at a specific position. Generally, the switching devices have aresponse time different from zero. The speed at which the moving objecttravels may differ in each instance, so that a large number of distancepulses would occur during the response time of the switching devices andexact synchronization would be impossible.

The principal object of the invention is to provide new and improvedapparatus and a method for synchronizing digital distance pulsecounters.

An object of the invention is to provide apparatus and a method forsynchronizing digital distance pulse counters with accuracy, efficiency,effectiveness and reliability.

An object of the invention is to provide apparatus and a method forsynchronizing digital pulse counters with simplicity and rapidity.

ln accordance with the present invention, apparatus for synchronizing adigital distance pulse counter for a moving object comprises a pulsegenerator coupled to a moving object for producing distance pulsescorresponding to the travel position of the moving object. A stationaryswitch having a defined response time is positioned along the travelpath of the moving object. The switch provides a signal for multiplyingthe distance pulses produced during n times the response period by thefactor l+yn). A lead counter has inputs coupled to the pulse generatorand to the switch for storing the distance pulses and the signalprovided by the stationary switch. A distance pulse counter is coupledto the pulse generator and to the lead counter in a manner whereby thedistance pulse counter is reset in accordance with the count position ofthe lead counter.

The distance pulses produced by the pulse generator are additionallysupplied to the lead counter upon the termination of the response timeand until a specific count position is attained by the lead counter.

A monostable multivibrator is coupled between the switch and the leadcounter and has a set time corresponding to the response time of theswitch. The monostable multivibrator magnetically operated switch memberfor resetting the monostable multivibrator.

A frequency multiplier may be connected between the switch and the leadcounter for multiplying the number of signals supplied by the switch.The lead counter comprises a multistage dual counter.

A bistable multivibrator is operated by the switch and is adapted torelease the lead counter to set the lead counter to a zero countposition.

A NOR gate is connected between the lead counter and the distance pulsecounter for providing an output signal which sets the individual stagesof the distance pulse counter at a specific count position and resetsthe bistable multivibrator.

The apparatus synchronizes a digital distance pulse counter for anelevator moving in a mine shaft and further comprises driving meanscoupled to the elevator for moving the elevator up and down. A rotarydigitizer is coupled to the driving means for producing pulses inaccordance with the angular position of the driving means. At least asingle switch is positioned in the mine shaft between two storing pointsof the elevator. At least two AND gates have inputs connected to therotary digitizer in a manner whereby the pulses provided by the rotarydigitizer control the conductivity condition of the AND gates, inaccordance with the direction of rotation of the rotary digitizer. TheAND gates have outputs connected to the distance pulse counter. Theoutput of the NOR gate is connected to each of the stages of thedistance pulse counter via the AND gates.

In accordance with the invention, a method for synchronizing a digitaldistance pulse counter for a moving object comprises the stepsofproducing distance pulses corresponding to the travel position of amoving object, providing a signal for multiplying the distance pulsesproduced during a response period, storing and counting the distancepulses and the signal, counting the distance pulses, and resetting thecount of the distance pulses in accordance with the initial countthereof.

lt is thus seen from the foregoing that the basic principle of myinvention is to regain the pulses accumulated during the responseperiod, in a subsequent period corresponding to the response time, withthe assistance of a multiplication of the pulses produced. After thetermination ofthe interval in which the distance pulses produced aremultiplied, the count position ofthe lead counter will correspondexactly to the distance from the stationary switch device, at a uniform,but unknown, velocity of the moving object. The count position of thelead counter is then utilized to correct the distance pulse counter.

The correction of the distance pulse counter by the lead counter may beeffected by known digital adders. In accordance with may invention,however, it is considerably less complicated, to supply the lead counterwith distance pulses after the termination of the response time anduntil the lead counter attains a specific count position. When the leadcounter attains such count position, the distance pulse counter needsonly to be set at one and the same count position. This requires aconsiderably lower output.

When the lead counter is supplied with distance pulses after theexpiration of the multiplying period, the bistable mu]- tivibrator isoperated by the stationary switching device and releases the leadcounter and resets it to zero. The count posi tion of the leadcountermay be readily evaluated in a particularly simple manner by utilizingthe NOR gate connected between the lead counter and the inputs of thedistance pulse counter. The output signal of the NOR gate sets theindividual counting stages of the distance pulse counter to a specificcount position and also resets the bistable multivibrator.

When the apparatus of my invention is utilized for mine equipment, arotary digitizer is mechanically coupled to the motor driving unit forthe elevator and'corresponds to the angular position of said motordriving unit.

If the object moves in two directions, the pulse counter may besynchronized in a simple manner by connecting the output of the NOR gateto the counting stages of the distance pulse counter via at least twoAND gates which are controlled in their conductive condition by outputsignals from the rotary digitizer, in accordance with the rotarydirection thereof.

In order that the present invention may be readily carried into effect,it will now be described with reference to the accompanying drawings,wherein:

FIG. 1 is a block diagram of an embodiment of the apparatus of theinvention for synchronizing digital distance counters;

FIG. 2 is a block diagram of the lead counter 24 of FIG. 1; and

FIG. 3 is a block diagram of a modified part of the apparatus of theinvention utilizing a monostable multivibrator with any desired resettime.

FIG. 1 illustrates the apparatus and method of the invention applied toan elevator or mine cage 3 moving in a mine shaft 2. The elevator 3 ismoved up and down by a driving pulley l. A pulley drive 4 is coupled tothe driving pulley l and rotates said pulley either clockwise orcounterclockwise to move the elevator 3 upward or downward in the mineshaft 2. A pulse generator 5 is mechanically coupled to the pulley drive4. The pulse generator 5 may comprise any suitable mechanicallymotivated pulse generator, such as, for example, a rotary digitizercomprising a nonmagnetic circular disc having a magnetizable peripherallayer which is magnetized at equiangular distances or intervals atalternating magnetic polarities. The magnetic indications on the discare scanned and sensed by two Hall generators.

When the driving pulley l is rotated by the pulley drive 4 to move theelevator 3 up and down in the mine shaft 2, the pulse generator 5produces pulses I at its output I. The number of pulses I produced bythe pulse generator 5 is proportional to the angle of rotation of thedriving pulley l. The direction of rotation of the driving pulley l isdetermined by a termination signal produced at the outputs V and R ofthe pulse generator 5. When the driving pulley 1 rotates in acounterclockwise direction, so that the elevator 3 moves downward in themine shaft 2, the pulse generator 5 produces an output pulse V at itsoutput V. When the driving pulley 1 rotates clockwise, so that theelevator 3 is moved upward in the mine shaft 2, the pulse generator 5produces an output pulse R at its output R.

The pulses l, which indicate the travel distance of the elevator 3, aresupplied to a pulse former 6 which converts them to rectangular pulses.The output of the pulse former 6 is supplied to an input ofa distancepulse counter 7 via leads 6a and 7a. The output pulses or signals V ofthe pulse generator 5 are supplied to an adding or positive input of thedistance pulse counter 7 via leads 5a and 7b. The output pulses orsignals R ofthe pulse generator 5 are supplied to the negative input ofthe distance pulse counter 7 via leads 5b and 7c. The pulses supplied tothe positive input of the distance pulse counter 7 are counted in thenormal additive sequence of said counter and the pulses supplied to thenegative input are counted in the reverse or negative sequence ordirection.

The distance pulse counter 7 has a plurality of outputs 10 connecteddirectly to an optical indicating device 11 via leads 10a and Ila andalso connected directly to an evaluating device 12 via leads 10a and10b. The evaluating device 12 functions to produce delay commands whichare supplied to the pulley drive 4 during an intended stop of theelevator 3 in the mine shaft 2, in accordance with the count position ofthe distance pulse counter 7. The delay commands produced by theevaluating device 12 may be supplied to a regulating device, not shownin the FIGS. The delay commands are produced by the evaluating device 12in a known manner and in accordance with the travel path of the elevator3.

In the aforedescribed manner, the distance pulse counter 7 projects theinstantaneous position of the elevator 3 in the mine shaft 2. In orderto correct errors caused by a slip of the cable supporting the elevator3, the skipping ofa pulse, or the inclusion of an interfering pulse, oneor more mine shaft switches, such as the switches 14 and 13, are mountedon the wall of the mine shaft 2. The mine shaft switches 13 and 14 areoperated by a magnet affixed to the cage or elevator 3 during the travelof said cage past the corresponding one of said switches.

A shaft switch is mounted at each possible stop or halting point of theelevator 3, so that the initiated delay of the pulley drive, inaccordance with the travel of said elevator, causes said elevator tostop with the best possible accuracy, at the intended stopping point.The stopping point is determined, in the illustrated example, by atunnel or seam 16, the position of which indicates the distance C, fromthe opening or mouth of the mine shaft 2.

The seam 16 is provided with a mine shaft switch 13 which indicates thedistance A, from the opening of the mouth of the mine shaft 2. Theresponse time of the shaft switch 13 is known. A magnet 15 is mounted onthe elevator 3. When the magnet 15 passes the shaft switch 13, movingupward, in the direction of the arrow, the working contact of the shaftswitch 13 is closed, and said shaft switch supplies a binary signal 1.The binary signal 1 provided by the shaft switch 13 is supplied by asource L of direct voltage.

The binary 1 signal supplied by the shaft switch 13 is suppliedsimultaneously to an input 17 ofa bistable multivibrator v or flip-flop18 and to the input of a monostable multivibrator or flip-flop 19. Thebinary 1 signal provided by the shaft switch 13 is supplied to thebistable multivibrator 18 via a lead 17a and is supplied to the input ofthe monostable multivibrator 19 via a lead 17b and an OR gate 36. Thebistable multivibrator 18 thus produces a binary l signal at its output20 and the monostable multivibrator 19 produces a binary l signal at itsoutput 21.

The binary 1 signal at the output 20 of the bistable multivibrator 18 issupplied to an AND-gate 23 via an OR gate 22, so that when the I pulsesproduced by the pulse generator 5 are supplied to said AND gate, saidpulses are transferred by said AND gate to an input 38 of the leadcounter 24 via a lead 38a. The set time of the monostable multivibratorl9 corresponds to the response time of the shaft switch 13. Upon thetermination of the set time of the monostable multivibrator 19, thesignal at the output 21 of said monostable multivibrator changes frombinary l to binary 0. The changed signal at the output 21 of themonostable multivibrator 19 effects the count of the lead counter 24 bybeing supplied to an input 39 of said lead counter 24 via an inverter 25and a lead 21a. When a binary 0 signal is supplied thereto, the inverter25 supplies a pulse to the lead counter 24 which doubles the countposition of said lead counter.

At the time that the output signal at the output 21 of the monostablemultivibrator 19 is binary 0, and if the cage 3 continues to move upwarduniformly, the count position of the lead counter 24 corresponds exactlyto the distance of the magnet 15 on said cage from the shaft switch 13.The pulses I produced by the pulse generator 5 are also supplied to thelead counter 24, which counts said pulses until it indicates a countposition which corresponds to a specific distance B from the shaftswitch 13. The distance B from the shaft switch 13 is preferablyselected so that it is greater than the path travelled by the elevator 3at the maximum feasible velocity thereof, during the response time ofthe shaft switch 13.

Upon the arrival of the magnet 15 at the predetermined counting positionB, a pulse appears, during the subsequent pulse interval of the pulsesequence I produced by the pulse generator 5, at an output 27 of aNOR-gate 26. Due to the pulse at the output 27 of the NOR-gate 26, abinary 1 signal occurs at the output of an AND-gate 29 during the upwardtravel of the elevator 3, and at the output of an AND-gate 28 during thedownward travel os said elevator. The operating magnet 15 on theelevator 3 is then located exactly in a position S, or 8,. The positionS, is a distance A, B from the mouth of the mine shaft 2. The position8, is a distance A, B from the mouth of the mine shaft 2.

The output signals of the AND gates 28 and 29 are supplied tocorresponding inputs of the distance pulse counter 7 and supplied toindividual counting stages of said pulse counter. The outputs of theAND-gates 28 and 29 are so connected to the corresponding inputs of thepulse counter 7 that a binary 1 signal provided at the output of theAND-gate 29 moves the count position of said counter to one whichcorresponds to the path distance A B. The outputs of the AND-gates 28and 29 are so connected to the corresponding inputs of the pulse counter7 that a binary 1 signal provided at the output of the AND-gate 28 movesthe count position of said counter to one which corresponds to the pathdistance A, B; this being ef fective only during the downward travel ofthe elevator 3.

When a binary 1 signal is provided at the output 27 of the NOR-gate 26,the bistable multivibrator I8 is simultaneously switched to its resetcondition. The bistable multivibrator 18 therefore produces a binarysignal at its output 20, which signal switches and AND-gate 23 to itsnonconductive condition, so that said AND gate blocks further pulses Ifrom the pulse generator 5. The binary l signal which is produced at theoutput 30 of the bistable multivibrator 18 at the same time, is suppliedto the lead counter 24 via a lead 30a and an OR-gate 37. Such binary 1signal moves the count position of the lead counter 24 back to zero, sothat said lead counter is then prepared for the next succeedingsynchronizing operation.

Analogously, the distance pulse counter 7 may be synchronized atpositions S and S. by utilizing an additional shaft switch 14, anadditional bistablemultivibrator 31, and additional AND-gates 34 and 35.In arder to expand the apparatus to more than four synchronizingpositions, it is only necessary to provide each additional shaft switchwith a bistable multivibrator and two AND gates, and to connect theworking contact of the shaft switch to another input of the OR-gate 36.Thus, the apparatus and method of my invention are simple and reliablein projecting the travel path of moving objects, and may be applied,without special measures, for both directions of travel, and may beexpanded at a minimum cost for an arbitrary number of synchronizingpositions.

FIG. 2 illustrates the lead counter 24 of FIG. 1 in greater detail. Theinputs and outputs are identified by the same reference numerals as inFIG. 1. The components of FIG. 1 shown in FIG. 2 are identified by thesame reference numerals. The lead counter 24 comprises a four stage dualcounter. The individual counting stage outputs are indicated by Z Z Zand 2,. The complementary counting stage outputs are 2, 2 Z, and Z Inthe counter illustrated in FIG. 2, the maximum counting capacity is 2 or16 units.

The count position of the dual counter doubles in a particularly simplemanner, since the information content or data of one counting stage istransferred to the next succeeding stage. To accomplish this, theoutputs of the individual counting stages Z, to Z and Z, to Z, arealways connected to prepared inputs of the next succeeding countingstages, and the releasing inputs of all the counting stages areconnected to the input terminal 39.

A signal at the input terminal 39, which changes from binary 0 to binary1 thus transfers the count position of each counting stage to the nextadjacent counting stage so that the count position is altogether doubled. The inputs of the complementary counting stages Z to Z, areconnected to the output ofthe OR-gate 37. Thus, a binary 1 signal at theoutput of the OR gate 37 switches the four counting stages to a positionwherein the complementary counting stages 2, to 2., provide a binary 1signal. The lead counter 24 is thus switched to a zero count position.

Conversely, when the counter reaches its highest count position, whichis 16 in the embodiment of FIG. 2, and corresponds to the path positionBof FIG. 1, all the complementary counting stages 2, to Z have zerosignals. During the next succeeding pulse intervals of the pulsesequence I produced by the pulse generator of FIG. I, a zero signal isproduced as the input terminal 40 of the NOR-gate 26 and a binary 1signal is provided at the output 27 of said NOR gate.

In the embodiment of FIGS. 1 and 2, the reset period of the monostablemultivibrator 19 corresponds exactly to the response time of the mineshaft switch. As a result of this, the pulses arriving during the resettime are doubled. In the modification of FIG. 3, the reset time of thebistable multivibrator 18 may be n times the reset time of the mineshaft switch 13. Thus, even in this case, the pulses which are notmeasured, that is, which are lost during the reset time of the shaftswitch 13, are regenerated and the pulses producedduring the reset timeof the bistable multivibrator 18 by the pulse generator 5 are multipliedby a factor. l+l /n.

When n=l, the pulses are doubled, as in the embodiment of FIG. I. Theonly difference is that in FIG. 1, the doubling of the pulses iseffected after the reset time of the bistable multivibrator 18, bydoubling the count position of the lead counter 24. In the embodiment ofFIG. 3, however, the doubling of the pulses is effected during the resetperiod by continuous frequency multiplication of the input pulsesequence.

In the modification of FIG. 3, only that portion of the circuit whichdeviates from the embodiment of FIG. I is illustrated. The samecomponents of FIGS. 1 and 3 are identified by the same referencenumerals. The output lead 6a of the pulse generator 6 is connected tothe input ofa frequency multiplier 41. The frequency multiplier 41multiplies the pulse sequence few to its input by an arbitrary factor byan appropriate setting of its input switches, indicated in FIG. 3 by aseries of horizontal arrows. I

The frequency multiplier is a known unit and is described, for example,in Austrian Pat. No. 241,860. The multiplication factor of the frequencymultiplier 41 is adjusted in a manner whereby it has the value 1+l/n,wherein n is the ratio of the reset period of the monostablemultivibrator 19 to the response time T of the shaft switch 13. Theoutput of the frequency multiplier 41 is supplied to one input of anAND- gate 42. The other input of the AND-gate 42 is connected to theoutput of the monostable multivibrator 19. The monostable multivibrator19 has a reset time nT.

When the monostable multivibrator 19 is operative in the mannerdescribed with reference to FIG. I, so that a binary 1 signal isprovided at the output 21 in said monostable multivibrator, and AND-gate43 is switched to its nonconductive condition by the binary 0 signalwhich is then produced at the output of an inverter 44. The AND-gate 42remains in its conductive condition.Thus, for the duration of the resetperiod, the pulses multiplied by the factor l+l/n may arrive at theinput 38 of the lead counter 24 via an OR-gate 45, as in FIG. I, whereinthe AND-gate 23 is utilized.

On the other hand, when the monostable multivibrator 19 has returned toits stable condition, during which a binary 0 signal is provided at itsoutput terminal 21, and AND-gate 43 is in its conductive condition andthe AND-gate 42 is in its nonconductive condition. Thus, the pulsesproduced by the pulse generator 5 may be directly supplied to theAND-gate 23.

The modification of FIG. 3 permits the utilization of a monostablemultivibrator stage with substantially any desired reset time. The resettime of the monostable multivibrator is adjusted to the response time ofthe mine shaft switch 13, in a manner hereinbefore described, by anappropriate setting of the multiplication factor of the frequencymultiplier 41. A dual counter is a counter operating in a dual code, incontrast to a decimal counter which operates as a binary coded decimalcounter. In this type of counter, the individual counter stages are soarranged that a number of increasing magnitude results from the primenumber 2. A code jump does not occur. Doubling may be effected in anespecially simple manner by shifting the contents of the individualcounter stages by one counter stage. This may be released by anespecially simple binary signal, whereupon each counter stage assumesthe contents ofthe adjacent lower valent counter stage.

While the invention has been described by means of specific examples andin specific embodiments, I do not wish to be limited thereto, forobvious modifications will occur to those skilled in the art withoutdeparting from the spirit and scope of the invention.

Iclaim:

1. Apparatus for synchronizing a digital distance pulse counter for amoving object. said apparatus comprising pulse generating means coupledto a moving object for producing distance pulses corresponding to thetravel position of said moving object; stationary switching means havinga defined response time positioned along the travel path of said movingobject, said switching means providing a signal for multiplying thedistance pulses produced during a number n times the response time bythe factor l+l/n); lead counting means having inputs coupled to saidpulse generating means and to said stationary switching means forstoring said distance pulses and the signal provided by said stationaryswitching means; and

distance pulse counting means coupled to said pulse generating means andto said lead counting means in a manner whereby said distance pulsecounting means is reset in accordance with the count position of saidlead counting means.

2. Apparatus as claimed in claim 1, wherein the distance pulses producedby said pulse generating means are additionally supplied to said leadcounting means upon the termination of the response time and until aspecific count position is attained by said lead counter.

3. Apparatus as claimed in claim 1, further comprising a monostablemultivibrator coupled between said stationary switching means and saidlead counting means and having a set time corresponding to the responsetime of said switching means, said monostable multivibrator producing anoutput signal for said lead counting means to enhance the count positionof said lead counting means, and wherein said switching means comprisesa magnetically operated switch member for resetting said monostablemultivibrator.

4. Apparatus as claimed in claim 1, further comprising a frequencymultiplier connected between said stationary switching means and saidlead counting means for multiplying the number of signals supplied bysaid pulse generating means during the response time of said switchingmeans, and wherein said switching means comprises a magneticallyoperated switch member.

5. Apparatus as claimed in claim 3, wherein said lead counting meanscomprises a multistage dual countert 6. Apparatus as claimed in claim 5,further comprising a bistable multivibrator operated by said switchingmeans and adapted to release said lead counting means from pulses fromthe pulse generating means and to set said lead counting means to a zerocount position.

7. Apparatus as claimed in claim 6, further comprising a NOR gateconnected between the lead counting means and the distance pulsecounting means for providing an output signal which sets the individualstages of said distance pulse counting means at a specific countposition and resets the bistable multivibrator.

8. Apparatus as claimed in claim 7, for synchronizing a digital distancepulse counter for an elevator moving in a mine shaft, further comprisingdriving means coupled to said elevator for moving said elevator up anddown, a rotary digitizer coupled to said driving means for producingpulses in accordance with the angular position of said driving means,and atleast a single stationary switch positioned in said mine shaftbetween two stopping points of said elevator.

9. Apparatus as claimed in claim 8, further comprising at least two ANDgates having inputs connected to said rotary digitizer in a mannerwhereby the pulses provided by said rotary digitizer control theconductivity condition of said AND gates in accordance with thedirection of rotation thereof and outputs connected to said distancepulse counting means, and wherein the output of said NOR gate isconnected to each of the stages of said distance pulse counting meansvia said AND gates.

1. Apparatus for synchronizing a digital distance pulse counter for amoving object, said apparatus comprising pulse generating means coupledto a moving object for producing distance pulses corresponding to thetravel position of said moving object; stationary switching means havinga defined response time positioned along the travel path of said movingobject, said switching means providing a signal for multiplying thedistance pulses produced during a number n times the response time bythe factor (1+1/n); lead counting means having inputs coupled to saidpUlse generating means and to said stationary switching means forstoring said distance pulses and the signal provided by said stationaryswitching means; and distance pulse counting means coupled to said pulsegenerating means and to said lead counting means in a manner wherebysaid distance pulse counting means is reset in accordance with the countposition of said lead counting means.
 2. Apparatus as claimed in claim1, wherein the distance pulses produced by said pulse generating meansare additionally supplied to said lead counting means upon thetermination of the response time and until a specific count position isattained by said lead counter.
 3. Apparatus as claimed in claim 1,further comprising a monostable multivibrator coupled between saidstationary switching means and said lead counting means and having a settime corresponding to the response time of said switching means, saidmonostable multivibrator producing an output signal for said leadcounting means to enhance the count position of said lead countingmeans, and wherein said switching means comprises a magneticallyoperated switch member for resetting said monostable multivibrator. 4.Apparatus as claimed in claim 1, further comprising a frequencymultiplier connected between said stationary switching means and saidlead counting means for multiplying the number of signals supplied bysaid pulse generating means during the response time of said switchingmeans, and wherein said switching means comprises a magneticallyoperated switch member.
 5. Apparatus as claimed in claim 3, wherein saidlead counting means comprises a multistage dual counter.
 6. Apparatus asclaimed in claim 5, further comprising a bistable multivibrator operatedby said switching means and adapted to release said lead counting meansfrom pulses from the pulse generating means and to set said leadcounting means to a zero count position.
 7. Apparatus as claimed inclaim 6, further comprising a NOR gate connected between the leadcounting means and the distance pulse counting means for providing anoutput signal which sets the individual stages of said distance pulsecounting means at a specific count position and resets the bistablemultivibrator.
 8. Apparatus as claimed in claim 7, for synchronizing adigital distance pulse counter for an elevator moving in a mine shaft,further comprising driving means coupled to said elevator for movingsaid elevator up and down, a rotary digitizer coupled to said drivingmeans for producing pulses in accordance with the angular position ofsaid driving means, and at least a single stationary switch positionedin said mine shaft between two stopping points of said elevator. 9.Apparatus as claimed in claim 8, further comprising at least two ANDgates having inputs connected to said rotary digitizer in a mannerwhereby the pulses provided by said rotary digitizer control theconductivity condition of said AND gates in accordance with thedirection of rotation thereof and outputs connected to said distancepulse counting means, and wherein the output of said NOR gate isconnected to each of the stages of said distance pulse counting meansvia said AND gates.